I can answer that! On my 2004 Turbo I had the coolant pipes fail. I had them repaired by my local Porsche dealer... And 48 hours later suffered the known collateral damage of having my transmission seals go out due to the leaking coolant eating them up. The starter is the other known collateral damage from pipe failure. It becomes much more expensive to fix if you wait till failure!

 

When it fails it fills up the area below the intake with coolant essentially drowning the starter. After that it is not much time till the starter goes. Also there is evidence that the coolant gets to the torque converter seal, affecting it, and that will then start leaking. (my 05 did)
It WILL fail. Do it on your time schedule.
It actually is already broke from the factory, hence the class action lawsuit and using aluminium for the replacement.
Just do it.

Edit. did not see the post above. Just went straight into my 2 cents.

 

Let's see... why I replaced them prior to them breaking:

1. I was going across the country in the Cayenne, and having them explode somewhere in the middle of nowhere might be a tad inconvenient. And awfully expensive. Flatbedding a Cayenne a 600 miles to the nearest dealer wouldn't be covered by AAA, nor would the hotel room/meals cost for the time the vehicle was laid up.

2. There are many reported cases of them taking out the input shaft seal on the transmission when they fail - when the coolant leaks down around it and turns into a hard crystaline substance with abrasive properties. That's about a $3,000 repair.

3. There are many cases of them taking out the starter when they go. That's not as bad - a new Porsche starter is only around $500 or so - and is easily done when you're doing the pipes that failed and caused it to fail.

But - continue on with "If it an't broke don't fix it" and let us know how that works out for you long term.

EDIT: - me too, but he deserves at least a dimes worth of 2 cents's..

 

Were you asking about the coolant pipes or the valve body? The coolant pipes plenty of folks have responded why to replace before they fail. The valve body there is no reason to replace it unless it starts going bad.

 

All the points mentioned above are exactly why I want to replace the coolant pipes ahead of time. Especially since this is a car that my dad will be driving around in. Thank you all for weighing in.

I reached out to all the dealerships in my area just to see what the price is to compare with what my indy will potentially charge. Funny to add this to the thread, given the overall consensus, but...here's the response from one of the dealership's service manager:

"I haven’t done coolant pipes in the last year or two. They don’t all break. It depends on a lot of variables… driven at high RPMs all the time, under weight duress of heavy cargo, lack of regular service, etc, etc. But to answer your question, that service ranges from $2200 to $2600 depending on how the items under the intake manifold look.

There are of course other things that can go wrong, but not to every vehicle as well, so we hate to replace parts that are not broken. But to your point, no one likes to be stuck on the side of the road.

We do a full vehicle inspection on every service to try and avoid those situations."

 

The reason they haven't done that job in a year or two is that almost all of the cayennes with the weak plastic pipes have enough miles/time on them that they have almost all been done already. If we did a survey here, I would hazard to guess very few 03-06 V8's have not had the plastic pipes fail. Oh, and on a vehicle inspection the pipes cannot be seen. The intake needs to be removed for that. If you have a good indy just print out the ECS instructions and give that to them. They would be able to do it anyway, but there are a few tricks and hidden connections described that will save the time of figuring out.

 

He might as well replace it. And reduce risk of having starter issues down the road and have to take the whole thing apart again.

 

Those were my thoughts exactly - I posted the service manager's reply because it just shocks me that after all these years and all these Cayenne's needing it they are still borderline denying the fault. go figure.

I will print out the instructions for my indy and let him take a look. Going to get this done within the next few weeks and most likely will replace the starter since we're down there. Thanks again for all your help!

 

I take very very good care of my truck, what ever it needs gets done. Porsche serviced.

 

I was referring to both. But people are very salty about the coolant pipes.

 

If the Indy doesn't understand how to do it they could screw it up more... Make sure they 100% know how to do it.

 

The ECS instructions don't really cover how difficult it can be to get the ends of the old pipes out of the aluminum they go into. That can be a real chore. There are several threads around (probably on RennList or RennTech) that will give you some ideas on how to make removal easier without damaging the hole the new pipes have to seal on.

FWIW - my independent is a belt/suspenders kinda guy, so he also put some RTV sealant around each of the O rings on the fittings that go into holes in the engine castings. He then let it sit 24 hours to make sure the RTV had setup before refilling the coolant. I can report there were no leaks.